This invention generally relates to vascular catheters suitable for maintaining the patency of a blood vessel after a vascular procedure therein, such as, an angioplasty procedure.
In typical percutaneous transluminal coronary angioplasty (PTCA) procedures, a guiding catheter having a preformed distal tip is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral arteries and advanced therein until the distal tip thereof is in the ostium of the desired coronary artery. A guidewire and a dilatation catheter having a balloon on the distal end thereof are introduced through the guiding catheter with the guidewire slidably disposed within an inner lumen of the dilatation catheter. The guidewire is first advanced out of the guiding catheter into the patient's coronary vasculature until the distal end thereof crosses the lesion to be dilated and then the dilatation catheter is advanced over the previously advanced guidewire until the dilatation balloon is properly positioned across the lesion. Once in position across the lesion, the flexible, relatively inelastic balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., greater than about 4 atmospheres) to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall to thereby dilate the lumen of the artery. The balloon is then deflated so that the dilatation catheter can be removed and blood flow resumed through the dilated artery.
Further details of angioplasty procedures and the devices used in such procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,332,254 (Lundquist); U.S. Pat. No. 4,439,185 (Lundquist); U.S. Pat. No. 4,168,224 (Enzmann et al.); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 4,582,181 (Samson) U.S. Pat. No. 4,597,755 (Samson); U.S. Pat. No. 4,616,652 (Simpson); U.S. Pat. No. 4,748,982 (Horzewski et al.); U.S. Pat. No. 4,771,778 (Mar et al.); U.S. Pat. No. 4,793,350 (Mar et al.), which are hereby incorporated herein in their entirety.
Steerable dilatation catheters with built-in guidewires or guiding elements are being used with greater frequency because the deflated profile of such catheters are generally smaller than conventional dilatation catheters having the same inflated balloon size. Further details of low-profile steerable dilatation catheters may be found in U.S. Pat. No. 4,582,181 (Samson) which is hereby incorporated in its entirety by reference thereto. The lower profile of these catheters allows the catheter to cross tighter lesions and to be advanced much deeper into the patient's coronary anatomy. Moreover, the use of steerable low-profile dilatation catheters having a built-in guidewire or guiding element shortens considerably the time for the angioplasty procedures because there is no need to first advance a guidewire into the patient's coronary anatomy to a desired location therein and then advance a conventional dilatation catheter over the previously inserted guidewire.
Frequently, the stenotic plaque or intima of the blood vessel or both are dissected during angioplasty procedure by the inflation of the balloon, so that upon the deflation of the balloon the dissected lining or flap will collapse, closing off blood flow through the vessel and thereby abruptly stopping or significantly reducing the passage of blood therethrough. In these instances, emergency bypass surgery is usually required to avoid a myocardial infarction distal to the blockage.
A dilatation catheter which also allows for the perfusion of blood distally of the catheter when the balloon is inflated, such as described in U.S. Pat. No. 4,790,315, could be used but such intravascular devices have relatively large profiles which may preclude their advancement through the blockage and thus leave emergency bypass surgery as the only recourse.
Copending application Ser. No. 283,729, filed Dec. 13, 1988, describes an intravascular catheter having an expandable cage on the distal end thereof which is designed to hold a detached lining against an arterial wall for extended periods to facilitate the reattachment thereof. However, this vascular device does not have effective means to guide the device through tortuous coronary anatomy.
What has been needed and heretofore unavailable is a steerable low-profile intravascular device which can be readily advanced through or around a flap which collapses within the bloodstream and which can maintain the patency of the blood vessel by holding the flap against the vessel wall for sufficient time to cause the natural adhesion of the flap to the vessel wall while simultaneously allowing for the perfusion of blood to locations distal to the catheter. The present invention satisfies that need.